I am now working on exercises of Wenham's "The Elements of New Testament
Greek" and have come across a problem. In Lesson 33 Exercise A-1, the
sentence goes;

OUAI, OUCI hH YUCH PLEION ESTIN THS TROFHS;

My question is about PLEION. Why is this adjective used in the neuter
form despite the fact that the other nouns ("hH YUCH" and "THS TROFHJ")
are both feminine? A feminine form, or the nominative feminine singular
form ("PLEIWN") should be used here, shouldn't it? If I am making a
very simple mistake, I will apologize.